Top Senate Republicans are calling on President Donald Trump — and his former chief strategist Stephen Bannon — to quit threatening Republicans with primary challenges when they do not support the administration.

"I wish they would focus on Democrats instead of Republicans," Sen. John Cornyn of Texas, the No. 2 Senate Republican, said when asked about reports Bannon is eyeing primary challenges to GOP incumbents who he thinks are not supportive of Trump, The Hill reported.

Sen. John Thune of South Dakota, the No. 3 Senate Republican, added the potential primary threats could make it harder for Republicans to hold on to their thin 52-seat majority despite a favorable 2018 map, The Hill reported.

"It does [make it harder], and it's not particularly productive. . . . We ought to stay focused on the task at hand," Thune told reporters.

The president also has lashed out at GOP senators, including Flake, Tennessee Sen. Bob Corker and Majority Leader Mitch McConnell of Kentucky.

Cornyn said Trump and his allies would be "well advised to focus on growing our number of Republicans in the Senate rather than diminishing it," The Hill reported.

"The president's going to need as many friendly faces around here as he can get in order to get things done," he said. "I realize that bipartisanship is important, but he shouldn't mistake a smile for support when it really counts."

According to The Hill, the threat of intra-party fighting worries congressional leaders who want to avoid situations where candidates defeat GOP incumbents in primaries only to lose in the general election.

"We intend to play in primaries if there's a clear choice between someone who can win in November and someone who can't," the majority leader said earlier this year, The Hill reported.

GOP Sens. Dean Heller of Nevada and Flake are the two Republican senators widely considered most vulnerable, The Hill reported.

Top Senate Republicans are calling on President Donald Trump, and his former chief strategist Stephen Bannon, to quit threatening Republicans with primary challenges when they do not support the administration.